Machine gun structure



Jan. 16, 1940. s. s. GREEN MACHINE GUN STRUCTURE Filed June 29, 1958 3Shqets-Sheet 1 h Inventor Samuel [3. Green Atturw gy Jan. 16, 1940. s.e. GREEN MACHINE GUN STRUCTURE 3 Sheets-Sl aeet 2 Filed June 29. 1938Inventor- Eamual G Gr'Ee L .Attnr'ne 3m 16, 1940- s. G. GREEN 2,1863%MACHINE GUN STRUCTURE Filed June 29, 1958 3 Sheets-Sheet 3 isI- I Atturn iay I 17 Claims.

(Granted under the act of March 8, 1883, as amended April 30, 1928; 3700. G. 757) instances by a recoil mechanism and in other instances by themount. In either instance there is some movement of the gun and itssupporting structure.

Since there will always be a recoil and counterrecoil movement when agun is fired it is desired to fire the gun in such a way as not to setup secondary periodic vibrations to add to this back and forth swing;otherwise the movement would become so irregular as to render the gunand movement unstsble,-entirely destroy the aim and probably causeinjury to the gun or mount.

The conventional method of firing the gun is to maintain the trigger onthe gun in the actuating position so that the gun fires when the breech.bolt is near the closed position regardless of the position of thegun'in its cycle of recoil and counterrecoilf- In the present inventionthe trigger on the gunis maintained in inoperative position except at apredetermined position of recoil and counterrecoil both as to the boltfiring mechanism represented by the firing pin sear and the gun as aunit represented by the gun receiver frame and the trigger and triggerslide carried thereby.

The purpose of the invention, then, is to pro-! vide means for socontrolling the firing of an automatic or semi-automatic gun having arecoil variable elevation that, after the first shot, it will alwaysfire at the proper position during a cycle of recoil, which firingposition is just in rear of the in battery position of the bolt an gunreceiver frame.

By in battery position is meant the normal position of the gun when notsubjected to the stresses and strains of firing, and the cycle of recoilrefers to the complete cycle of vibration forwardly and rearwardly.

A further object of the invention is to provide a simple-and compactrecoil mechanism for a free mounted cradle, that is, one in whichelevation is directly controlled by the gunner.

To these and other ends, the invention consists in the construction,arrangement and combination of elements described hereinafter andpointed out in the claims forming a part of this specification.

A practical embodiment of the invention is illustrated in theaccompanying drawings, wherein:

Fig. 1 is a view in side elevation, with parts broken away and parts insection of. a machine gun mounted for recoil on a cradle;

Fig. 2 is a longitudinal sectional view of the recoil mechanism; 1

Fig. 3 is a view in side elevation and partly in section of the recoilslide;

Fig. 4 is a sectlcnalvlew on the line 4-4 of Fig. 2;

Fig. 5 is a. plan view with parts in the gun mounted in the cradle;

Fig. 6 is an enlarged sectional view of the firing mechanism with theparts in position of rest ready to fire the first shot;

Fig. 7 shows -,the firing mechanism with the parts in automatic firingrelationship;

Fig. 8 is a detail view in side elevation of the actuator slide andbracket;

Fig. 9 is a sectional view on the line 9-9 of Fig. 8;

Fig.1!) is a plan view of the frame for the recoil mechanism; ,1

Fig. 11 is a sectional view of the cradle plate taken on the line ll--ilof Fig. 1.

Referring to the drawings by characters of reference there is shown amachine gun of the Browning type employed in the armed services of thiscountry comprising a receiver frame A having a rearapertured bracket B(Fig. 1) and front trunnions C (Fig. 5). A breech bolt D reciprocallymounted within the gun frame and normally held in battery by a drivingspring (customarily not shown) {carries a firing pin E which isretracted by a cocking lever F associated with the gun frame in sucha-manner that the firing pin is automatically out of firing positionexcept section of 29 firing pin in cocked position is movable to releasethe firing pin by a sear slide H.

One side of the gun frame carries a trigger mechanism which is similarto that shown in my prior Patent No. 2,069,244 of February 2, 1937, andincludes a housing 6 (Figs. 5 and 6) in which a trigger G is pivotallymounted at its front end and normally held in inoperative position by aspring i. The rear part of the trigger 'is provided on its inner sidewith a lug 8 adapted to project through an opening in the gun frame toengage the sear slide and trip the sear. The rear face of the lug isformed with a cam surface 9 which is adapted to actuate the sear slideH, as the bolt approaches the final movement of its counterrecoilstroke.

The outer side of the trigger is formed with a cam surface it adapted tobe engaged by the cam surface ii on the inner side of a trigger slide l2during retraction of said slide. The slide i2 is mounted in the housingand is normally held in a iorward position by a spring it. A lug i l onthe outer side of the trigger slide is adapted to be engaged by anactuator that is independent of the recoiling gun frame as willbeexplained hereinafter.

The gun is mounted for recoil and counterrecoil movement in a cradlewhich comprises spaced plates l-l5 and is mounted for movement inelevation on trunnion studs iii-i8 (Fig.- 11) threaded in a pintle W. Asleigh iii disposed between the front ends of the cradle plates 05 isslidably mounted on a pair of spaced, longitudinally arranged shaftsiQ-lg (Figs. 1 and 5) each of which is fixed in a bracket 2t secured toa cradle plate. The sleigh is provided with half-bearings for receivingthe gun trunnions C-C which are retained by means of pivoted clamps iii.A nut 22 mounted on the front end of each shaft and externally threadedto the bracket forms a seat for one end of a buffer spring 23. The otherend of the spring is seated on a collar 24! which is slidable on theshaft and is held against a shoulder 25 on the shaft by means of thespring. The rear faces of the collars 20 on the shafts are adapted to beengaged by the sleigh.

The rear apertured bracket B on the gun is attached by means of a pin 26to apertured ears 2l2i on the slide 28 of a recoil mechanism or brake.In order to facilitate insertion of the pin which is passed through aslot 29 in the left cradle plate, the alignment of the apertures in thebracket and ears is insured by means of a lug 30 in the slide 28 whichengages astop finger M. The finger 3i is on the inner end of a shaft 32which is mounted in elements of the right cradle plate and carries ahandle 33. A torsion spring (it normally rotates the shaft to move thefinger out of the path of the lug (it. When the lug is in engagementwith the finger, the resilient elements of the recoil mechanism exertsufficient pressure to prevent the action of the torsion spring fromdisengaging the finger 3i from the lug 30, but after the first shot isfired and the slide moves rearwardly, the finger automatically returnsto disengaged position under influence of the torsion spring.

The slide 28 of the recoil mechanismv is mounted on a tube 35, (Figs. 1and 2) which is carried by a frame 3t fixed to the cradle and whichincludes cross pieces 37 and 38 having central bearings, respectively370. and 38a, for receiving the tube. The tube is inserted through thebearings until a collar 39 engages the rear face of the rear cross piece37 when lock nuts W are turned on the tube to bear against the frontface of the rear cross piece. The front end of the tube bears against aretainer ring M which is held by a plug 62 threaded in the front crosspiece bearing 88c.

a ieaeca The slide 28 consists of a large cylinder 2801 (Figs. 1, 3 and4) slidably mounted on the outside of the tube and a small cylinder 2%disposed within the tube and connected to the large cylinder by webs 28cwhich ride in slots '43 in opposite side walls of the cylinder. Theouter end of the small cylinder 2% carries an adjusting plug (i ithreaded to the interior of the cylinder.

Within the tube and near its center is a nut 35 which positions atubular plug it. A helical main spring All is confined between the plug56 and the inner endof the small cylinder 281). An auxiliary helicalspring 58 disposed Within the main spring is confined between theadjusting plug at and a socket 419 on a cross head 5t (Figs. 2, 5 and10) which extends through opposite slots 5l5i (Fig. 1) in the rear endportion of the tube 335. The socket seats against a retainer plate 52secured to the end of the tube by screws 53. A guide rod 5Q secured tothe socket passes through the spring 4t and has its front end slidablyreceived in the adjusting plug a l.

A pair of rack bars Evie-55 (Figs. 5, and 10) slidably mounted in theframe 35 include cylindrical rear extremities 565, for slidably'mounting the ends of the cross-head 56) between a shoulder 51 and a nut58, the nut 58 normally bearing against the cross-head at zero elevationand! serving when the rack bars are moved forwardly to correspondinglymove the cross head to compress the springs and shorten the recoilstroke relative to its horizontal position by increasing the force ofrestitution of the springs. During depression of the gun from zeroelevation, the rack bars are moved rearwardly but no change takes placein the spring adjustment because the cross head is held by the retainerplate 52.

The front end of each rack bar includes an arcuate rack 5 meshing with acompound pinion 60 which is pivotally mounted on a pin 6i carried by thecradle plate. The pinion 60 also meshes with a gear segment 62 fixed tothe pintle ll so that when the cradle is rotated about the trunnionstuds it the rack bars will be displaced to vary the recoil stroke ofthe gun. As shown in Fig. l the relation of rack gears 59 with respectto the cooperating gear segments on compound gears 60 is such thatmovement of the rack bars 55-55 will be proportional to the cosine oftheangle through which gears 60 are rotated.

The trigger slide actuating mechanism (Figs.

6, 8 and 9) is carried by the left cradle plate and comprises a supportor housing member 63 ad- Justabiy secured to the cradle plate by bolts64. It is formed with spaced fianges 65-455 between which an actuatorslide 66 is mounted. The slide 66 is provided with a lug 6'! adapted toengage the lug M of the trigger slide I2. A laterally projecting ear 68on the rear end of the slide is apertured to receive a rod 69 which hasa collar it bearing against the rear face of the ear. A second collar Hon the rod intermediate its ends is arranged to bear against anapertured ear 12 on the housing and forms a seat for one end of ahelical spring '53 which is seated on the inner face of the ear (it. Asecond spring it is confined between the ear l2 and an ear on the frontend of the actuator slide.

A link it pivotally connected to the rear end of the rod 69 is alsopivotally connected to one arm of a lever llll which is pivotallymounted on a pin lsattached to the housing. A second link 19 pivoted tothe outer arm of the lever I1 is also pivoted to a hand operated lever80 pivotally mounted in a bracket 8| adjustable on the back rest $2.

- When the hand lever 80 is pressed down against the back rest 82, therod 69 is retracted and acting through the spring 13 it causesretraction of the actuator slide 86. The lug 61 is thereby movedrearwardly into engagement with the lug M on the trigger slide in orderto fire the first shot, and it has a further rearward displacement of M;of an inch to properly position it for firing subsequent shots.

The hand lever 80 when held against the back rest is not subjected tovibrations and firing impulses.

The housing 63 is inscribed with a reference line 83 which is readableagainst a scale 86 on the left cradle plate, and which is graduated invalue of of an inch with a heavy line 85 indicating the average setting.The back rest 82 is provided with a similar scale 86 which is readagainst the front face of the bracket 8|. This scale 86 is used toadjust the rod 69 so that the collar 10 normally engages the ear 58 onthe rear of. slide 66.

The operation of the mechanism is as follows: With the parts in positionof rest, that is with the breech bolt in battery, the gun receiver framein battery, and the sear slide, and trigger in firing relationship, theactuator slide is retracted to initiate firing of the gun. The actuatorslide moves of an inch into engagement with the lug l6, and then anadditional of an inch, of which the first part is sufficient to swingthe trigger inwardly to trip the sear and the last part is over-travel.The breech bolt now moves in recoil and after traveling 7.2 inches it isreturned by its driving spring towards its in battery position. When thebolt is midway of its recoil, the reaction on the gun receiver framecauses it to move in recoil for a distance of about of an inch before itis moved in counterr'ecoil by the springs.

Since the trigger slide carried by the gun frame was initially retractedto fire the shot it does not partake of the corresponding initialmovement in recoil of the gun frame but it is later picked up by the gunframe. At the end of the recoil stroke of the gun frame, the triggerslide and the trigger have been restored by their springs to theirinitial position.

When the gun frame is moving in counterrecoil and is about of an inchout of battery the trigger slide engages the lug of. the actuator slideand the trigger is moved through the opening in the gun frame into thepath of the sear slide. At this time the sear slide on thecounterrecoiling breech bolt is from 1 5' to $6 of an inch from inbattery position and it then engages the inclined cam and is tripped.The next shot is actually fired when the bolt is from A; to $4; of aninch of its battery position. The-bolt and the gun frame receive theimpulse from the second shot and do not reach their in batterypositions. As a consequence the counterrecoil buffers function only onthe last shot.

The purpose in firing out of battery is to allow for variation infriction in the mount, bullet weight, velocity of bullet and variationsin gun recoil velocity, external and internal, and to obtain a reductionof 25% in recoil energy delivered to the mount for each shot after thefirst shot.

The mechanism as arranged fires the first and each succeeding shotsemiautomatically and it will be observed that this requires that thephase relation between the gun cycle and gun frame cycle be notdisturbed. Full gun cyclic rate may be maintained or even increased dueto the shorter recoil and therefore decreased period of recoil under theconditions hereinabove specified.

I claim:

1. A support, a gun frame mounted on the support for recoil andcounterrecoilmovement and having a normal in battery position, a breechbolt mounted within the gun frame for recoil and counterrecoil movementrelative thereto and having a normal in battery position, said gun frameand bolt having different lengths of recoil, a scar on thebolt, seartripping means on the gun frame including a trigger and a slidereciprocal with respect to the gun frame and trigger with each shot foractuating the trigger, said sear and sear tripping means having a firingrelationship for first shot firing when the gun frame and bolt are intheir in battery position and having a firing relationship for automaticfiring when the gun frame and bolt are approximately similar distancesin rear of their in battery positions, which automatic firingrelationship is sufflciently to the rear so that the gun frame and boltwill receive the impulse of the shot before reaching their in batterypositions,

means for moving and holding the sear tripping means out of the path. ofthe sear when these members are in rear of their position of automaticfiring relationship, and means carried by the support for moving thesear tripping means when the gun frame and bolt are in battery andsubsequently during automatic firing.

.2. The combination with a reciprocally mounted gun carryingseartripping means and housing a reciprocable breech bolt with a sear,of a fixed support adjacent the gun. a housing adiustably carried by thefixed support, a reference line on the housing, a'scale including a markfor normal setting provided on the fixed support and readable againstthe reference line, a slide movable in the housing and having means foractuably engaging the sear tripping means on the gun, an operating rodhaving means for limiting the rearward position of the slide, a springbetween the rod and slide for transmitting retraction of the rod to theslide, means for retracting the rod, and a bracket carrying saidretracting means and adjustable on the fixed support, a scale on thesupport for indicating normal setting of the bracket.

3. The combination with a reciprocally mounted gun carrying seartripping means and housing a reciprocable breech bolt with a sear, of afixed support adjacent the gun, a housing adjustably carried by thefixed support, a reference line on the housing, a scale including a markfor normal setting provided on the fixed support and readable againstthe reference line, a slide movable in the housing and having means foractuably engaging the sear tripping means on the gun, an operating rodhaving means for limiting the rearward position of the slide, a springbetween the rod and slide for transmitting retraction of the rod to theslide, and means for retracting the rod.

i. The combination with a reciprocally mounted gun carrying seartripping means and housing a reciprocable breech bolt with a sear, of afixed support adjacent the gun, a housing adjustably carried by thefixed support, a slide movable in the housing and having means foractuably engaging the sear tripping means on the gun, an operating rodhaving means for limiting the rearward position of the slide, a springbetween the rod and slide for transmitting retraction of the rod to theslide, and means for retracting the rod. 1

5. The combination with a reciprocally-mounted gun carrying seartripping means and housing a reciprocable breech bolt with a sear, of afixed support adjacent the gun, a slide movable on the fixed support andhaving means for actuably engaging the sear tripping means 'on the gun,a rod passing through the rear end of the slide and having a collarengageable with the fixed support, a spring confined between the rearend of the slide and the collar on the rod, means for retracting the rodto move the slide through the spring into position to yieldingly actuatethe sear tripping means, and a return spring seated on the fixed supportand engaging the slide.

6. The combination with a reciprocally mounted gun carrying seartripping means and housing a reciprocable breech bolt with a sear, of afixed support adjacent the gun, a slide movable on the fixed support andhaving means for actuably engaging the sear triping means on the gun,

a rod passing through the rear end of theslide and having a collarengageable with the fixed support, a spring confinedibetween the rearend of the slide and the collar on the rod, means for retracting the rodto move the slidethrough the spring into position to yieldingly actuatethe sear tripping means;

'7. In a mount for guns, a support, a cradle trunnioned thereon formovement in elevation, a tube fixed on the cradle, a recoil slidecomprising a large cylinder mounted on the outside of the tube and asmall cylinder mounted within the tube, an adjusting plug in the smallcylinder, an adjustable plug within the tube, an outer spring confinedbetween the adjustable plug and the small cylinder, an inner springhaving one end seated on the adjusting plug, a movable seat for theother end of the inner spring and means operable on elevation of thecradle for varying the position of the movable seat.

8. In a mount for guns, a cradle trunnioned for movement in elevation, arecoil slide mounted on the cradle, an adjusting plug in the slide, aspring having one end seated on the adjusting plug, a movable seat forthe other end of the spring, and means having a lost motion connectionwith the movable seat operable on elevation above the horizontal only ofthe cradle for varying the position of the movable seat.

9. In a mount for guns, a cradle trunnioned for movement in elevation, arecoil slide mounted on the cradle, a spring having, one end seated onthe slide, a movable seat for the other end of the spring, and meanshaving a lost motion connection with the movable seat operable onelevation above the horizontal only of the cradle for varying theposition of the movable seat.

10. In a mount for guns, a cradle trunnioned for movement in elevation,a recoil slide mounted on the cradle, a spring having one end seated onthe slide, a movable seat for the other end of the spring, means forlimiting rearward displacement of the movable seat under influence ofthe spring, and means operable on elevation only of the cradle fordisplacing the movable seat forwardly, said last named means having alost motion connection with the movable seat whereby it is movablerearwardly with respect to ars eoo the movable seat. on depresslon ofthe cradle below horizontal.

11. In a mount for guns, a cradle, a recoil slide mounted on the cradleand having gun attaching means, resilient means normally moving theslide forwardly on the cradle, a shaft mounted in the cradle, a fingeron the shaft for engaging the slide to predetermine the position of thegun attaching means, and a spring for moving the fingers out of the pathof the slide on retraction of the slide.

12. In a recoiling mounted automatic gun in combination, a supportrotatable in elevation, a

gun frame mounted on the support for recoil movement from a normalbattery position, recoil brake means having a force of restitutionadapted to be varied interposed between the support and gun frame andnormally holding said gun frame in its battery position, a recoilingbreech bolt mounted within said gun frame and having a normal batteryposition therewithin, firing mechanism adapted to fire the first shot ofa series with the breech bolt and gun frame in their respective-batterypositions and thereafter automatically displaceable to fire allsubsequent shots of said series in a predetermined counterrecoilposition of the breech bolt and gun frame, and means for maintainingsaid predetermined counterrecoil position of firing substantiallyconstant which includes mechanism for varying said force of restitutionin accordance with the angle of elevation of the support.

13. In a recoil mounted automatic gun in combination, a supportrotatable in elevation, a gun frame mounted on the support for recoiland counterrecoil movement at a uniform periodic cyclic rate and havinga normal battery position, recoil brake means interposed between thesupport and gun frame and normally holding said gun frame in its batteryposition under a restorative force, a breech bolt mounted in said gunframe for recoil and counterrecoil movement at a uniform periodic cyclicrate and phase relation in advance of that of the gun frame and having anormal battery position, firing mechanism actuable to fire the firstshot of a series to initiate automatic operation of the breech boltandgun frame in their respective phase relation and thereafterautomatically displaceable to fire all subsequent shots at apredetermined position of the breech bolt and gun frame in counterrecoilin the same said phase relation, whereby their cyclic rates will beincreased, and means for maintaining the cyclic rate of the-breech boltand gun frame uniform through various angular positions of the supportwhich includes mechanism automatically operable by movement of thesupport in elevation to vary said restorative force.

14. In a recoiling mounted automatic gun, in combination, a support, agun frame mounted on the support for recoil movement from a normalbattery position, a recoiling breech bolt mounted within said gun frameand having a normal battery position therewithin firing mechanismincluding a cam actuable trigger and cam means adapted to actuate thetrigger operatively mounted on the gun frame and a resiliently loadedactuator mounted on the support and adapted to actuably engage the cammeans, resilient means normally holding said cam means in inoperativeposition and means for displacing said actuator to engage and displacethe cam means and trigger in the battery position of the breech bolt andgun frame to fire a first shot and thereafter automatically displaceableto actuably engage 55 areaseo said cam means in a predeterminedcounterrecoil position of the breech bolt and gun frame to firesucceeding shots.

15. In a mount'for guns, a cradle comprising a pair of parallel sideplates adapted to-be mounted for rotation in elevation, a recoil brakemountedon the rear portion of the cradle between said side plates,across head secured to the recoil brake in operative relation to varythe force of restitution thereof upon movement, a rack bar secured toeither arm of said cross head and extending forwardly ofthe cradle,racks on said rack bars and compound pinions on the side plates engagingsaid racks and adapted to be engaged by pinionafixed on a support forthe cradle.

16. In a mount for guns, a cradle comprising a pair of parallel sideplates adapted to be mounted for rotation in elevation, a frame providedwith guide means mounted on the rear portion of the cradle between theside plates, a slotted tubular member having spring retaining means atits front and rear ends mounted longitudinally of the cradle in saidframe, a spring compressed within the tubular member between saidretaining means, a cross head having arms protruding through the slotsinterposed between the rear spring retaining means and corresponding endof the spring, complementary rack bars extending forwardly of the cradleand slidably mounted in said guides. means securing the rear ends of therack bars to the cross head arms for relative movement, arcuate racksattached to the forward ends of the rack bars and compound pinionshaving complementary gear sectors engaging said racks, whereby the forceof restitution of said spring may be varied as a function of theelevation of the cradle.

17. In a trigger mechanism a support member having an ear intermediateits ends, a trigger actuating slide mounted on the support member withend portions disposed on either side of said ear, an operating roddisposed substantially par allel to the slide and having a collarnormally engagingthe ear, resilient means interposed between the collarand one end portion of the slide on one side of said ear fortransmitting movement of the operating rod in one direction to the slideand additional resilient means interposed between the ear and the otherend portion of the slide on the opposite side of said ear.

SAMUEL G. GREEN.

